Derby Talk

Derby Talk is a forum for Pinewood Derby, Awana Grand Prix, Kub Kar Rally, Shape N Race Derby, Space Derby, Raingutter Regatta and other similar races where a child and an adult work together to create a race vehicle and a lot of fun and memories

As some may recall my first experience with my Tiger last year had some bumps with an out of spec car getting through tech and winning.
This year we were going to be forced to race on January 2nd (too close to the holidays in my opinion). The track we borrowed last year is also not available for the weekend we want to race later in January. The Pack owns a 3 lane wooden track that has not been used in years.

Thanks to strong recruitment and strong popcorn sales the Pack has decided to purchase a track and timing system. Guess who got put in charge?

Tonight I ordered a 4 lane 42' Best Track, 4 lane Fast Track K2K timer, and looked into upgrading our GPRM 2.0 software. I suggested that we do this over the summer, but they wanted to get popcorn sales complete to make sure we met our goals. We will now race in late January since we have a track and can control our own destiny to some degree. Lots of work between now and then for me. I will likely be asking for some advice.

I am thinking of racing each scout once in each lane and using total time to determine overall Den winners. Depending on the length of the race day we can have a finals with perhaps the top two in each den racing each lane again...

Last edited by race#67 on Sun Jan 31, 2016 8:11 am, edited 2 times in total.

race#67 wrote:As some may recall my first experience with my Tiger last year had some bumps with an out of spec car getting through tech and winning.
This year we were going to be forced to race on January 2nd (too close to the holidays in my opinion). The track we borrowed last year is also not available for the weekend we want to race later in January. The Pack owns a 3 lane wooden track that has not been used in years.

Thanks to strong recruitment and strong popcorn sales the Pack has decided to purchase a track and timing system. Guess who got put in charge?

Tonight I ordered a 4 lane 42' Best Track, 4 lane Fast Track K2K timer, and looked into upgrading our GPRM 2.0 software. I suggested that we do this over the summer, but they wanted to get popcorn sales complete to make sure we met our goals. We will now race in late January since we have a track and can control our own destiny to some degree. Lots of work between now and then for me. I will likely be asking for some advice.

I am thinking of racing each scout once in each lane and using total time to determine overall Den winners. Depending on the length of the race day we can have a finals with perhaps the top two in each den racing each lane again...

Sounds pretty sweet! I asked to buy another section of track for our Microwizard Track to lengthen it to 40', and and I got a tepid response, because they were afraid the track wouldn't fit our venue anymore...

Anyhow! Make sure you read up on how to polish and deburr a fresh BestTrack! Also, might look into some of the mods that gpraceman posted, regarding the starting gate and suchlike.

For finals, I would suggest that you take whatever the number of trophy slots (e.g. 1st, 2nd, 3rd) you have for the finals and promote that number of cars from each group to the finals race.

Vitamin K wrote:Sounds pretty sweet! I asked to buy another section of track for our Microwizard Track to lengthen it to 40', and and I got a tepid response, because they were afraid the track wouldn't fit our venue anymore...

Personally, I don't think that it is worth the money to get a longer track.

I have a 40ft MW track and haven't used the last section for years now. Why? Because running it at the 32 ft length makes it much easier for the less competitive cars to at least cross the finish line. Nothing is more heart breaking to a kid than to watch their car race and not even finish.

Vitamin K wrote:Sounds pretty sweet! I asked to buy another section of track for our Microwizard Track to lengthen it to 40', and and I got a tepid response, because they were afraid the track wouldn't fit our venue anymore...

Personally, I don't think that it is worth the money to get a longer track.

I have a 40ft MW track and haven't used the last section for years now. Why? Because running it at the 32 ft length makes it much easier for the less competitive cars to at least cross the finish line. Nothing is more heart breaking to a kid than to watch their car race and not even finish.

I agree that's a sad thing to watch. Though, we've had cars that failed to make it across the finish line on the 32 footer, too. I try to send out as much car building advice as I can, but I can't force parents to actually read it.

If I can somehow get my practice track built over the holidays, I'd like to bring it to our check-in (which is two days before the actual race) and set it up in the hallway, sans timer, and let kids send their cars down it for a practice run to catch any catastrophic issues before race day.

I still would like a longer track. I like the way it gives a little more spread between the cars to really make the winners stand out. Then again, that's from the perspective of somebody who likes to build fast cars...

Vitamin K wrote:I agree that's a sad thing to watch. Though, we've had cars that failed to make it across the finish line on the 32 footer, too. I try to send out as much car building advice as I can, but I can't force parents to actually read it.

If I can somehow get my practice track built over the holidays, I'd like to bring it to our check-in (which is two days before the actual race) and set it up in the hallway, sans timer, and let kids send their cars down it for a practice run to catch any catastrophic issues before race day.

For the races that I run for local Awana clubs, we rarely have any cars not finish. We test run each car down the track individually, before the race, and any that don't finish get sent to the pits.

Vitamin K wrote:I still would like a longer track. I like the way it gives a little more spread between the cars to really make the winners stand out. Then again, that's from the perspective of somebody who likes to build fast cars...

Personally, I think it is more exciting to see closer finishes (assuming that there is a working timer to distinguish the winners). If I had to eyeball judge, I would want the longer track.

Yep, I certainly have GPRM V2. I even have the computer they ran it on! I have tossed the computer and am now looking to upgrad to Lite or Pro.

We made sure every car was brought up to at least 4.8 ozs last year on a borrowed 42' track, and all of them finished.

I am trying to finalize the rules for this year. Last years rules stated stock slots must be used, and left open. Kit axles and kit wheels were the only ones acceptable.

I am considering making any officially licensed STOCK wheels and axles legal. This would allow the Revell axles which for the average person are a much better option. I would also like to allow drilled axle holes, since the stock slots can be a nightmare.
Thoughts?

race#67 wrote:Yep, I certainly have GPRM V2. I even have the computer they ran it on! I have tossed the computer and am now looking to upgrad to Lite or Pro.

We made sure every car was brought up to at least 4.8 ozs last year on a borrowed 42' track, and all of them finished.

I am trying to finalize the rules for this year. Last years rules stated stock slots must be used, and left open. Kit axles and kit wheels were the only ones acceptable.

I am considering making any officially licensed STOCK wheels and axles legal. This would allow the Revell axles which for the average person are a much better option. I would also like to allow drilled axle holes, since the stock slots can be a nightmare.
Thoughts?

For our district, we (well, I guess I was the driving force behind it) borrowed heavily from the Northern Star Council rules for our upcoming race for this Scouting year. In my opinion, the NSC did a good job selecting a ruleset that made for verifiable rules, and did a good job of letting builders have a nice amount of freedom, while preventing success from being all about the high dollar parts.

Regarding axles, if you allow Revell axles, then why not allow Max-V or Awana axles too? And if you allow any kind of axle, how do you intend to check to see what somebody happens to be using? There aren't many non-destructive ways of verifying axles. Even if you require them to be in open slots, you can buy 'copycat' axles that still look like BSA axles.

Of course, verifiability isn't everything, and different groups have different ideas of what's fair. Just sharing what felt like a good ruleset for us.

Yes, I see your point. My point on the Revell axles is that you can get them at our Scout Shop, and they say Officially Licensed BSA on them. TO me that makes it easy for the average or below average skilled parent to stop somewhere and pick them up if they are not up to learning how to make the junk kit axles work well.
Once you open the door to the pandora's box of internet speed goodies, in my opinion the intent of the event has been skewed. I know about the copycat axles, and even wheels that cannot be detected to be lightened that carry the name of a cat that sounds like 'cheater'. Sad.
To some degree I have to trust the parents to be intent on teaching their kids the right way to compete. I probably should know better than to do that after what happened last year.

Here is what I have come up with so far, a mix of Northern Star, BASX, and our traditional rules. I am open to critiques:

DESIGN RULES:
Wheel Base : Any as long as wheels do not exceed the 7″ total length requirement
Total Car Height : Not to exceed 3″
Total Car Length : Not to exceed 7″
Total Car BODY Width : Not to exceed 1-3/4″
Underside Clearance : Minimum 3/8"
Total Car Weight : Not to exceed 5.0 ounces (+.04) or 143 grams even measured on 1/10th digital scale.

BODY:
Wood from the Official BSA Grand Prix Pinewood Derby Kit must be used to construct your own body and/or frame. Additional construction accessories are encouraged for decorative purposes as long as the items comply with dimensional rules. No loose materials of any kind are permitted on the car. No springs or rubber shocks.

Officially Licensed BSA Axles & Wheels must be installed to the side of the car body directly across from one another / No more than a 10 degree angle. There must be at least four wheels on the car, however, it is not required that all four wheels make contact with the track surface.

WHEELS:
a. May be sanded to remove burrs and mold marks or to true the edge of tread, surface and circumference
b. The tread / contact surface must remain flat and parallel to the bore as humanly possible
c. No Angling, Reshaping, Canting, Round Crowning, Tapering, H-ing, V-ing, Dishing, the outside of the wheels and/or tread surface
d. All markings must remain visible on the inside and outside of the wheel including tread bumps.
e. NO Wheel covers may be used
f. 8.00mm Minimum Tread Width
g. Wheels must weigh at least 2.4 grams and a wheel can be removed after the race to be weighed to confirm weight.
h. Internet purchased modified 'speed wheels' are strictly prohibited.

WEIGHT:
Weight should be added to the car to get close to the 5.0 ounce maximum, but must be firmly attached by permanent glue, nails or screws.

LUBRICANT:
Dry lubricants are the only lubricants permitted. These include Graphite and Powdered Teflon. The use of liquid and spray lubricants such as WD-40, sewing machine oil and others is expressly prohibited.

GRAVITY POWERED:
The race car may not be constructed or treated in such a way that the track's starting mechanism imparts momentum to the car. (For instance, this provision disqualifies cars with sticky substances on the front of the car and protrusions which may catch on the starting pin.)

Looks like a decent rule set, to me. We decided to allow oil this year, since it was being sold at the Scout Store now.

One thing we're doing is to purchase Krytox and better axles and make them available to the boys (we might ask for a buck for the axles...not sure yet), just so that everybody's got access to the same stuff.

We had a weight restriction in last years' rules, but I dropped it, because I didn't feel like weighing a wheel was something we'd ever do. Instead, we're focusing on keeping the wheels to a minimum diameter and tread width, and prohibiting inside material removal. My goal is to teach the inspectors how to spot lathe marks on the inside of a wheel, and also to spot those cuts that leave a thicker inner lip while the rest of the inside tread is shaved down.

Given that you require them to use the wood from the kit, I assume you're not permitting pre-cut bodies? We had a prohibition on these once, but since some parents are far less inclined towards woodworking than others, we decided to allow them back in. (Though, last year, a car built from the Revell Batmobile kit won a design award. I was kind of annoyed at that , because you shouldn't win a design award from a pre-made kit. Oh well.)

Thanks VK, more good points to consider.
I already sent this to my Pack Committee to ponder on possibly allowing liquid lubricants:

"Pro's: If a scout shows up with no lubricant at all, we could quickly and CLEANLY add some to the car to give them a faster car.
Cons: We could end up with some cars shoeing up dripping in oil. Also a scout that did no lubrication prep could end up quicker than a graphited car as the liquids are generally considered better than poorly applied graphite. Also the high end liquid lubricants are expensive, and not available in stores."

I just checked and sure enough it shows up on Scoutstuff.org. Not sure if it is in the stores here. The $21.99 price is a big con. Now what you guys are doing is an excellent idea.

You also raise a good point on the pre-cut cars. One I will bring up to our committee. One good thing we do is several of us take our scroll saws, bandsaws, and sanders to the meeting place one nigh and we have an optional cutout night for everyone in the pack. That gives the boys and parents without the resources a chance to really get involved in designing and creating a car.

The wheel rule is one I struggle with. It all stems from last year, when a car (the Cub Masters sons car to boot) beat everybody else by a wide margin. Although myself and another well informed Den Leader did all of the checking in, that car was checked in by her in our absence. The other Den Leader spotted the lightened wheels right away. They were *really* lightened. No BSA logos on the inside, hollowed out sidewall. It was her sons last year and she claimed he and his uncle built the car and that she had no idea what they did. Our rules last year said no lathing or lightening, but did not elaborate more.

My brother is a very accomplished machinist. We were wondering if you could machine a wheel and not see the marks. I took one of the new wheels to him (we were accustomed to machining CMI wheels back in the day when it was legal!). With a sharp tool, high speed, and a low feed on a CNC lathe...the surface finish difference cannot be detected by the naked eye.

My Humble opinion. Keep the stock wheelbase for everyone. An extended wheelbase car cannot easily be accomplished by the majority of folks and gives the car a definite advantage. Leave the extended wheelbase cars for the "OUTLAW" race.

Also, pulling a wheel is going to ruin the cars alignment and it might be impossible to regain the cars speed for a District race.

race#67 wrote:
My brother is a very accomplished machinist. We were wondering if you could machine a wheel and not see the marks. I took one of the new wheels to him (we were accustomed to machining CMI wheels back in the day when it was legal!). With a sharp tool, high speed, and a low feed on a CNC lathe...the surface finish difference cannot be detected by the naked eye.

That is a bit of concern. At this point, it's too late to change our guidelines, but it might be something I need to think more about next time around.

speedster wrote:
My Humble opinion. Keep the stock wheelbase for everyone. An extended wheelbase car cannot easily be accomplished by the majority of folks and gives the car a definite advantage. Leave the extended wheelbase cars for the "OUTLAW" race.

I dunno, if you can drill an axle hole, you can extend your wheelbase. Or, if you can cut a slot, you can do the same. The little slip of paper that comes with the car tells how to re-cut slots, if need be.

Also, I'm not convinced of the advantage of extended wheelbases. If you look at the cars winning in the (ahem) non-Scout races, a lot of them run wheelbases around 4.5 - 4.75 inches. The full extended wheelbases seem to have fallen out of favor.

Now, on an old wooden track with more bumps, you might get better benefits from extending the wheelbase, but I know that our boys will be racing on aluminum at both pack and district level.

Again guys, I appreciate the discussion. I am not well versed in the nuances of some of these decisions yet.

I agree, pulling a wheel would be a last resort. Unless I saw evidence of it that made me 100% certain, I would likely not do it. I guess I hope that the *threat* of enforcement might deter the crime. Hope none of our pack racers are reading this, lol.

Also a good point on wheel base. Perhaps keeping them stock would seemingly level the playing field. Chances are the boys that have help motivated and talented enough to drill axle holes, are the ones that will do well. That makes the obviously extended wheelbase cars stand out, and the longer wheelbase becomes the perceived reason, not the alignment care or canting behind it.

This leads me to, and I am a bit off topic...but can someone point me to a well run test with numerical data on the advantages of canting? As I understand it the idea is to get the wheel to migrate to the head and stay there were there is less friction than against the body. This is a new theory from when I ran 30 years ago. To me the cant is FORCING the wheel against the head, which seemingly would create more friction than the wheel possibly alternating between a well prepped body and a well prepped nailhead assuming the wheel hub is prepped correctly too...

race#67 wrote:
This leads me to, and I am a bit off topic...but can someone point me to a well run test with numerical data on the advantages of canting? As I understand it the idea is to get the wheel to migrate to the head and stay there were there is less friction than against the body. This is a new theory from when I ran 30 years ago. To me the cant is FORCING the wheel against the head, which seemingly would create more friction than the wheel possibly alternating between a well prepped body and a well prepped nailhead assuming the wheel hub is prepped correctly too...

So, I'm not really convinced that canted axles give much gains in the friction department. Since friction is not dependent on surface contact area, I don't see gains to be made in terms of whether the wheel rides the head, or whether the hub touches the body (presuming that both contact points are equally lubed).

From my understanding, the biggest benefit to running canted wheels is to keep the rear wheels off of the rails in a rail rider configuration.

Our District (Four Peaks) has a good rules set that has evolved and improved through the years, and that is now being adopted by other Districts in Grand Canyon Council. We've made the rules modular, allowing uniform car specifications combined with flexible event rules.